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  <title>Truncates a large object</title>
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 <body class="docs"><div id="layout">
  <div id="layout-content"><div id="function.pg-lo-truncate" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">pg_lo_truncate</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.6.0, PHP 7)</p><p class="refpurpose"><span class="refname">pg_lo_truncate</span> &mdash; <span class="dc-title">
   Truncates a large object
  </span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.pg-lo-truncate-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>pg_lo_truncate</strong></span>
    ( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$large_object</code></span>
   , <span class="methodparam"><span class="type">int</span> <code class="parameter">$size</code></span>
   ) : <span class="type">bool</span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>pg_lo_truncate()</strong></span> truncates a large object
   resource.
  </p>
  <p class="para">
   To use the large object interface, it is necessary to
   enclose it within a transaction block.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.pg-lo-truncate-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">large_object</code></dt>

     <dd>

      <p class="para">
       PostgreSQL large object (LOB) resource, returned by <span class="function"><a href="pg_lo_open.html" class="function">pg_lo_open()</a></span>.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">size</code></dt>

     <dd>

      <p class="para">
       The number of bytes to truncate.
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.pg-lo-truncate-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
  </p>
 </div>

 
 <div class="refsect1 examples" id="refsect1-function.pg-lo-truncate-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-2504">
    <p><strong>Example #1 <span class="function"><strong>pg_lo_truncate()</strong></span> example</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />&nbsp;&nbsp;&nbsp;$doc_oid&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">189762345</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$database&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"dbname=jacarta"</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">pg_query</span><span style="color: #007700">(</span><span style="color: #0000BB">$database</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"begin"</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$handle&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">pg_lo_open</span><span style="color: #007700">(</span><span style="color: #0000BB">$database</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$doc_oid</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"r"</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;Truncate&nbsp;to&nbsp;0<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">pg_lo_truncate</span><span style="color: #007700">(</span><span style="color: #0000BB">$handle</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">0</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">pg_query</span><span style="color: #007700">(</span><span style="color: #0000BB">$database</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"commit"</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #0000BB">$data</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

   </div> 
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.pg-lo-truncate-changelog">
  <h3 class="title">更新日志</h3>
  <p class="para">
   <table class="doctable informaltable">
    
     <thead>
      <tr>
       <th>版本</th>
       <th>说明</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td>5.6.0</td>
       <td>
        Added truncate function. It supports PostgreSQL 9.3&#039;s 64bit large object. Both client and server must
        support PostgreSQL 9.3 and PHP must be 64bit build to use 64bit large object.
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
 </div>

 
 <div class="refsect1 seealso" id="refsect1-function.pg-lo-truncate-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="pg_lo_tell.html" class="function" rel="rdfs-seeAlso">pg_lo_tell()</a> - 返回大型对象的当前指针位置</span></li>
   </ul>
  </p>
 </div>

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